At the start of the Isaiah chapters in 2 Nephi, Isaiah, writing Messianically, poses this question: "O house of Israel, is my hand shortened at all that it cannot redeem, or have I no power to deliver?" (2 Nephi 7:2).
I believe this question is answered throughout the Isaiah chapters of the Book of Mormon. Perhaps the end of these writings best answers this question: "For notwithstanding I shall lengthen out mine arm unto them from day to day, they will deny me; nevertheless, I will be merciful unto them, saith the Lord God, if they will repent and come unto me; for mine arm is lengthened out all the day long, saith the Lord God of Hosts" (2 Nephi 28:32).
And as Christ later told Joseph Smith:
"For I am God, and mine arm is not shortened . . ."
D&C 35:8.
I testify that Christ's arm is not shortened; He can redeem!